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Raices M, D'Angelo MA. Structure, Maintenance, and Regulation of Nuclear Pore Complexes: The Gatekeepers of the Eukaryotic Genome. Cold Spring Harb Perspect Biol 2022; 14:a040691. [PMID: 34312247 PMCID: PMC8789946 DOI: 10.1101/cshperspect.a040691] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In eukaryotic cells, the genetic material is segregated inside the nucleus. This compartmentalization of the genome requires a transport system that allows cells to move molecules across the nuclear envelope, the membrane-based barrier that surrounds the chromosomes. Nuclear pore complexes (NPCs) are the central component of the nuclear transport machinery. These large protein channels penetrate the nuclear envelope, creating a passage between the nucleus and the cytoplasm through which nucleocytoplasmic molecule exchange occurs. NPCs are one of the largest protein assemblies of eukaryotic cells and, in addition to their critical function in nuclear transport, these structures also play key roles in many cellular processes in a transport-independent manner. Here we will review the current knowledge of the NPC structure, the cellular mechanisms that regulate their formation and maintenance, and we will provide a brief description of a variety of processes that NPCs regulate.
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Affiliation(s)
- Marcela Raices
- Cell and Molecular Biology of Cancer Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, USA
| | - Maximiliano A D'Angelo
- Cell and Molecular Biology of Cancer Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, USA
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2
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Bonnet A, Chaput C, Palmic N, Palancade B, Lesage P. A nuclear pore sub-complex restricts the propagation of Ty retrotransposons by limiting their transcription. PLoS Genet 2021; 17:e1009889. [PMID: 34723966 PMCID: PMC8585004 DOI: 10.1371/journal.pgen.1009889] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 11/11/2021] [Accepted: 10/18/2021] [Indexed: 11/19/2022] Open
Abstract
Beyond their canonical function in nucleocytoplasmic exchanges, nuclear pore complexes (NPCs) regulate the expression of protein-coding genes. Here, we have implemented transcriptomic and molecular methods to specifically address the impact of the NPC on retroelements, which are present in multiple copies in genomes. We report a novel function for the Nup84 complex, a core NPC building block, in specifically restricting the transcription of LTR-retrotransposons in yeast. Nup84 complex-dependent repression impacts both Copia and Gypsy Ty LTR-retrotransposons, all over the S. cerevisiae genome. Mechanistically, the Nup84 complex restricts the transcription of Ty1, the most active yeast retrotransposon, through the tethering of the SUMO-deconjugating enzyme Ulp1 to NPCs. Strikingly, the modest accumulation of Ty1 RNAs caused by Nup84 complex loss-of-function is sufficient to trigger an important increase of Ty1 cDNA levels, resulting in massive Ty1 retrotransposition. Altogether, our study expands our understanding of the complex interactions between retrotransposons and the NPC, and highlights the importance for the cells to keep retrotransposons under tight transcriptional control.
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Affiliation(s)
- Amandine Bonnet
- Université de Paris, Institut de Recherche Saint-Louis, INSERM U944, CNRS UMR 7212, Paris, France
- Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - Carole Chaput
- Université de Paris, Institut de Recherche Saint-Louis, INSERM U944, CNRS UMR 7212, Paris, France
| | - Noé Palmic
- Université de Paris, Institut de Recherche Saint-Louis, INSERM U944, CNRS UMR 7212, Paris, France
| | - Benoit Palancade
- Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - Pascale Lesage
- Université de Paris, Institut de Recherche Saint-Louis, INSERM U944, CNRS UMR 7212, Paris, France
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3
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Woldegebriel R, Kvist J, Andersson N, Õunap K, Reinson K, Wojcik MH, Bijlsma EK, Hoffer MJV, Ryan MM, Stark Z, Walsh M, Cuppen I, van den Boogaard MJH, Bharucha-Goebel D, Donkervoort S, Winchester S, Zori R, Bönnemann CG, Maroofian R, O’Connor E, Houlden H, Zhao F, Carpén O, White M, Sreedharan J, Stewart M, Ylikallio E, Tyynismaa H. Distinct effects on mRNA export factor GANP underlie neurological disease phenotypes and alter gene expression depending on intron content. Hum Mol Genet 2020; 29:1426-1439. [PMID: 32202298 PMCID: PMC7297229 DOI: 10.1093/hmg/ddaa051] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/17/2020] [Accepted: 03/19/2020] [Indexed: 11/15/2022] Open
Abstract
Defects in the mRNA export scaffold protein GANP, encoded by the MCM3AP gene, cause autosomal recessive early-onset peripheral neuropathy with or without intellectual disability. We extend here the phenotypic range associated with MCM3AP variants, by describing a severely hypotonic child and a sibling pair with a progressive encephalopathic syndrome. In addition, our analysis of skin fibroblasts from affected individuals from seven unrelated families indicates that disease variants result in depletion of GANP except when they alter critical residues in the Sac3 mRNA binding domain. GANP depletion was associated with more severe phenotypes compared with the Sac3 variants. Patient fibroblasts showed transcriptome alterations that suggested intron content-dependent regulation of gene expression. For example, all differentially expressed intronless genes were downregulated, including ATXN7L3B, which couples mRNA export to transcription activation by association with the TREX-2 and SAGA complexes. Our results provide insight into the molecular basis behind genotype-phenotype correlations in MCM3AP-associated disease and suggest mechanisms by which GANP defects might alter RNA metabolism.
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Affiliation(s)
- Rosa Woldegebriel
- Stem Cells and Metabolism Research Program, Research Programs Unit, University of Helsinki, 00290 Helsinki, Finland
- Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Jouni Kvist
- Stem Cells and Metabolism Research Program, Research Programs Unit, University of Helsinki, 00290 Helsinki, Finland
| | - Noora Andersson
- Department of Pathology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Research Program in Systems Oncology, University of Helsinki, Helsinki, Finland
| | - Katrin Õunap
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
- Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
| | - Karit Reinson
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
- Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
| | - Monica H Wojcik
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Divisions of Genetics and Genomics and Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Emilia K Bijlsma
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands
| | - Mariëtte J V Hoffer
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands
| | - Monique M Ryan
- Murdoch Children’s Research Institute, Melbourne 3052, Australia
- Royal Children’s Hospital, Melbourne 3052, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne 3052, Australia
| | - Zornitza Stark
- Murdoch Children’s Research Institute, Melbourne 3052, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne 3052, Australia
| | - Maie Walsh
- Murdoch Children’s Research Institute, Melbourne 3052, Australia
| | - Inge Cuppen
- Department of Pediatric Neurology, Wilhelmina Children’s Hospital, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Diana Bharucha-Goebel
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
- Division of Neurology, Children's National Health System, Washington, DC, USA
| | - Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Sara Winchester
- Child Neurology Center of Northwest Florida, Pensacola, FL, USA
| | - Roberto Zori
- Division of Genetics and Metabolism, University of Florida, Gainesville, FL, USA
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Reza Maroofian
- Department of Neuromuscular Disorders, UCL Institute of Neurology, London WC1N 3BG, UK
| | - Emer O’Connor
- Department of Neuromuscular Disorders, UCL Institute of Neurology, London WC1N 3BG, UK
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Institute of Neurology, London WC1N 3BG, UK
| | - Fang Zhao
- Department of Pathology and Genetics, HUSLAB Laboratories, Helsinki University Hospital, University of Helsinki, Helsinki, Finland
| | - Olli Carpén
- Department of Pathology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Research Program in Systems Oncology, University of Helsinki, Helsinki, Finland
| | - Matthew White
- Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Jemeen Sreedharan
- Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Murray Stewart
- MRC Laboratory of Molecular Biology, Francis Crick Ave, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Emil Ylikallio
- Stem Cells and Metabolism Research Program, Research Programs Unit, University of Helsinki, 00290 Helsinki, Finland
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, Finland
| | - Henna Tyynismaa
- Stem Cells and Metabolism Research Program, Research Programs Unit, University of Helsinki, 00290 Helsinki, Finland
- Department of Medical and Clinical Genetics, University of Helsinki, 00290 Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
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4
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Soheilypour M, Mofrad MRK. Quality control of mRNAs at the entry of the nuclear pore: Cooperation in a complex molecular system. Nucleus 2019; 9:202-211. [PMID: 29431587 PMCID: PMC5973141 DOI: 10.1080/19491034.2018.1439304] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Despite extensive research on how mRNAs are quality controlled prior to export into the cytoplasm, the exact underlying mechanisms are still under debate. Specifically, it is unclear how quality control proteins at the entry of the nuclear pore complex (NPC) distinguish normal and aberrant mRNAs. While some of the involved components are suggested to act as switches and recruit different factors to normal versus aberrant mRNAs, some experimental and computational evidence suggests that the combined effect of the regulated stochastic interactions between the involved components could potentially achieve an efficient quality control of mRNAs. In this review, we present a state-of-the-art portrait of the mRNA quality control research and discuss the current hypotheses proposed for dynamics of the cooperation between the involved components and how it leads to their shared goal: mRNA quality control prior to export into the cytoplasm.
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Affiliation(s)
- Mohammad Soheilypour
- a Molecular Cell Biomechanics Laboratory , Departments of Bioengineering and Mechanical Engineering, University of California , Berkeley
| | - Mohammad R K Mofrad
- a Molecular Cell Biomechanics Laboratory , Departments of Bioengineering and Mechanical Engineering, University of California , Berkeley
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5
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Goos C, Dejung M, Wehman AM, M-Natus E, Schmidt J, Sunter J, Engstler M, Butter F, Kramer S. Trypanosomes can initiate nuclear export co-transcriptionally. Nucleic Acids Res 2019; 47:266-282. [PMID: 30418648 PMCID: PMC6326799 DOI: 10.1093/nar/gky1136] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/25/2018] [Indexed: 02/03/2023] Open
Abstract
The nuclear envelope serves as important messenger RNA (mRNA) surveillance system. In yeast and human, several control systems act in parallel to prevent nuclear export of unprocessed mRNAs. Trypanosomes lack homologues to most of the involved proteins and their nuclear mRNA metabolism is non-conventional exemplified by polycistronic transcription and mRNA processing by trans-splicing. We here visualized nuclear export in trypanosomes by intra- and intermolecular multi-colour single molecule FISH. We found that, in striking contrast to other eukaryotes, the initiation of nuclear export requires neither the completion of transcription nor splicing. Nevertheless, we show that unspliced mRNAs are mostly prevented from reaching the nucleus-distant cytoplasm and instead accumulate at the nuclear periphery in cytoplasmic nuclear periphery granules (NPGs). Further characterization of NPGs by electron microscopy and proteomics revealed that the granules are located at the cytoplasmic site of the nuclear pores and contain most cytoplasmic RNA-binding proteins but none of the major translation initiation factors, consistent with a function in preventing faulty mRNAs from reaching translation. Our data indicate that trypanosomes regulate the completion of nuclear export, rather than the initiation. Nuclear export control remains poorly understood, in any organism, and the described way of control may not be restricted to trypanosomes.
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Affiliation(s)
- Carina Goos
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Mario Dejung
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany
| | - Ann M Wehman
- Rudolf Virchow Center, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany
| | - Elisabeth M-Natus
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Johannes Schmidt
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jack Sunter
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Markus Engstler
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Falk Butter
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany
| | - Susanne Kramer
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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6
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Toro-Ascuy D, Rojas-Araya B, García-de-Gracia F, Rojas-Fuentes C, Pereira-Montecinos C, Gaete-Argel A, Valiente-Echeverría F, Ohlmann T, Soto-Rifo R. A Rev-CBP80-eIF4AI complex drives Gag synthesis from the HIV-1 unspliced mRNA. Nucleic Acids Res 2019; 46:11539-11552. [PMID: 30239828 PMCID: PMC6265489 DOI: 10.1093/nar/gky851] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 09/12/2018] [Indexed: 12/15/2022] Open
Abstract
Gag synthesis from the full-length unspliced mRNA is critical for the production of the viral progeny during human immunodeficiency virus type-1 (HIV-1) replication. While most spliced mRNAs follow the canonical gene expression pathway in which the recruitment of the nuclear cap-binding complex (CBC) and the exon junction complex (EJC) largely stimulates the rates of nuclear export and translation, the unspliced mRNA relies on the viral protein Rev to reach the cytoplasm and recruit the host translational machinery. Here, we confirm that Rev ensures high levels of Gag synthesis by driving nuclear export and translation of the unspliced mRNA. These functions of Rev are supported by the CBC subunit CBP80, which binds Rev and the unspliced mRNA in the nucleus and the cytoplasm. We also demonstrate that Rev interacts with the DEAD-box RNA helicase eIF4AI, which translocates to the nucleus and cooperates with the viral protein to promote Gag synthesis. Finally, we show that the Rev/RRE axis is important for the assembly of a CBP80-eIF4AI complex onto the unspliced mRNA. Together, our results provide further evidence towards the understanding of the molecular mechanisms by which Rev drives Gag synthesis from the unspliced mRNA during HIV-1 replication.
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Affiliation(s)
- Daniela Toro-Ascuy
- Laboratory of Molecular and Cellular Virology, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Bárbara Rojas-Araya
- Laboratory of Molecular and Cellular Virology, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Francisco García-de-Gracia
- Laboratory of Molecular and Cellular Virology, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Cecilia Rojas-Fuentes
- Laboratory of Molecular and Cellular Virology, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Camila Pereira-Montecinos
- Laboratory of Molecular and Cellular Virology, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Aracelly Gaete-Argel
- Laboratory of Molecular and Cellular Virology, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Fernando Valiente-Echeverría
- Laboratory of Molecular and Cellular Virology, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Théophile Ohlmann
- INSERM U1111, CIRI, Lyon F-69364, France.,Ecole Normale Supérieure de Lyon, Lyon F-69364, France
| | - Ricardo Soto-Rifo
- Laboratory of Molecular and Cellular Virology, Virology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile
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7
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Pascual-Garcia P, Capelson M. Nuclear pores in genome architecture and enhancer function. Curr Opin Cell Biol 2019; 58:126-133. [PMID: 31063899 DOI: 10.1016/j.ceb.2019.04.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/28/2019] [Accepted: 04/02/2019] [Indexed: 01/28/2023]
Abstract
Nuclear genome architecture relies on interactions between the genome and various nuclear scaffolds. One such a nuclear scaffold is the nuclear pore complex (NPC), which in addition to its nuclear transport function, can interact with underlying chromatin. In particular, NPCs have been recently reported to associate with a number of enhancers and superenhancers in metazoan genomes, and select NPC components have been shown to promote the formation of specific genomic loops. Here, we provide a brief overview of current models of enhancer function, and discuss recent evidence that NPCs bind enhancers and contribute to topological genome organization. We also examine possible models of how gene and enhancer targeting to NPCs may contribute to tissue-specific genome architecture and expression programs, including the possibility that NPCs may promote phase separation of transcriptional compartments.
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Affiliation(s)
- Pau Pascual-Garcia
- Department of Cell and Developmental Biology, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Maya Capelson
- Department of Cell and Developmental Biology, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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8
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Soheilypour M, Mofrad MRK. Regulation of RNA-binding proteins affinity to export receptors enables the nuclear basket proteins to distinguish and retain aberrant mRNAs. Sci Rep 2016; 6:35380. [PMID: 27805000 PMCID: PMC5090210 DOI: 10.1038/srep35380] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 09/23/2016] [Indexed: 02/06/2023] Open
Abstract
Export of messenger ribonucleic acids (mRNAs) into the cytoplasm is a fundamental step in gene regulation processes, which is meticulously quality controlled by highly efficient mechanisms in eukaryotic cells. Yet, it remains unclear how the aberrant mRNAs are recognized and retained inside the nucleus. Using a new modelling approach for complex systems, namely the agent-based modelling (ABM) approach, we develop a minimal model of the mRNA quality control (QC) mechanism. Our results demonstrate that regulation of the affinity of RNA-binding proteins (RBPs) to export receptors along with the weak interaction between the nuclear basket protein (Mlp1 or Tpr) and RBPs are the minimum requirements to distinguish and retain aberrant mRNAs. Our results show that the affinity between Tpr and RBPs is optimized to maximize the retention of aberrant mRNAs. In addition, we demonstrate how the length of mRNA affects the QC process. Since longer mRNAs spend more time in the nuclear basket to form a compact conformation and initiate their export, nuclear basket proteins could more easily capture and retain them inside the nucleus.
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Affiliation(s)
- M. Soheilypour
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, CA, 94720, USA
| | - M. R. K. Mofrad
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, CA, 94720, USA
- Molecular Biophysics and Integrative Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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9
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Kramer S, Piper S, Estevez A, Carrington M. Polycistronic trypanosome mRNAs are a target for the exosome. Mol Biochem Parasitol 2016; 205:1-5. [PMID: 26946399 PMCID: PMC4850246 DOI: 10.1016/j.molbiopara.2016.02.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 02/26/2016] [Accepted: 02/29/2016] [Indexed: 11/02/2022]
Abstract
Eukaryotic cells have several mRNA quality control checkpoints to avoid the production of aberrant proteins. Intron-containing mRNAs are actively degraded by the nuclear exosome, prevented from nuclear exit and, if these systems fail, degraded by the cytoplasmic NMD machinery. Trypanosomes have only two introns. However, they process mRNAs from long polycistronic precursors by trans-splicing and polycistronic mRNA molecules frequently arise from any missed splice site. Here, we show that RNAi depletion of the trypanosome exosome, but not of the cytoplasmic 5'-3' exoribonuclease XRNA or the NMD helicase UPF1, causes accumulation of oligocistronic mRNAs. We have also revisited the localization of the trypanosome exosome by expressing eYFP-fusion proteins of the exosome subunits RRP44 and RRP6. Both proteins are significantly enriched in the nucleus. Together with published data, our data suggest a major nuclear function of the trypanosome exosome in rRNA, snoRNA and mRNA quality control.
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Affiliation(s)
- Susanne Kramer
- Biozentrum, Julius-Maximilians Universität Würzburg, Am Hubland, 97074 Würzburg, Germany; Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK.
| | - Sophie Piper
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Antonio Estevez
- Instituto de Parasitología y Biomedicina "López-Neyra", IPBL N-CSIC, Parque Tecnológico de Ciencias de la Salud, Avda. del Conocimiento, s/n.18100 Armilla, Granada, Spain
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
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